/Engine/Source/Runtime/Engine/Public/MaterialCompiler.h
This can be used to know if the strata tree we are trying to build is too deep and we should stop the compilation. This can be used by all nodes taking as input StrataData in order to detect node re-entry leading to cyclic graph we cannot handle and compile internally: we must fail the compilation.
virtual bool GetStrataTreeOutOfStackDepthOccurred()